The age-old problem of discouraging passengers from inserting objects into the reentry passage of an escalator handrail, and of avoiding injury to feet and hands which can be dragged into the entry by the motion of the handrail still persists. In the beginning, a simple plate with a slotted oval opening (sort of tee shaped) prevented objects and debris from entering the balustrades. However, the clearance required to avoid scratching of the visible top-surface portion of the handrail also provided the opportunity for injury to mall fingers and the like. Therefore, other types of guards were provided to the handrail reentry. A sponge rubber guard is illustrated in U.S. Pat. No. 2,708,997. But the resilience of such a guard allows small hands and arms (etc.) to be drawn significantly into the balustrade by friction with the moving handrail, thus causing different types of injuries. A flexible guard placed in front of a more solid guard is illustrated in U.S. Pat. No. 3,670,862. To avoid ingestion type injuries U.S. Pat. No. 3,970,187 provides a very close guard of foamed polystyrene which is adapted to crumble under pressure, such as the pressure imposed by a hand.
A different approach is to detect the intrusion of objects and sound alarms or shut the handrail down. An early intrusion detector is a microswitch having an actuator mounted in the path of an intruding object within the balustrade, as shown in U.S. Pat. No. 2,846,045. A variation therein is a hollow, pneumatically sealed guard connected to a pressure switch, such that any deflection thereof from an intruding object will raise the pneumatic pressure and operate the switch to shut down the handrail, disclosed in U.S. Pat. No. 2,848,093. However, the handrails have significant mass and do not stop immediately. Thus detecting the intrusion, after it has occurred, will generally not stop the handrail quickly enough to avoid injury, even injury caused by contacting the intrusion detector itself. Therefore, non-injurious detectors have been proposed, such as an electrostatic field intrusion detector illustrated in U.S. Pat. No. 5,001,495.
A further approach, in U.S. Pat. No. 5,001,459, has a guard that generally keeps debris and foreign objects out, but utilizes an intrusion sensor to physically open the guard when intrusion occurs, thereby tending to mitigate injury. However, these still have the problem of sufficiently rapid operation to avoid injuring intruding body parts on the one hand and keeping out unwanted debris and inserted objects on the other.
Still another approach includes having a very closely fitting guard which avoids gauging the handrail by being allowed to move somewhat therewith, one form of which is shown in U.S. Pat. No. 5,064,047.